Paul gmehlikt



(No Model.) 1 GMEHLIN.

KEY FRAME FOR PIANO FORTES. No. 356,759. Patented Feb. 1, 1887.

E52! a I i if 3 6 U W I I 2 4 r1 n H? v IL UNITED STATES PATENT OFFICE.

PAUL GMEHLIN, OF NEYV YORK, N. Y.

KEY-FRAME FOR PlANO-FORTES.

SPECIFICATION forming part of Letters Patent No. 356,759, dated February 1, 1887.

Application filed September 22. 1886. Serial No. 214,216. (No model.)

.To aZZ whom, it may concern.-

Be it known that 1, PAUL GMEHLIN, a resident of New York city, in the county and State of New York, have invented an Improvement in Key-Frames for Piano-Fortes, of which the following is a full, clear, and exact description, reference being made to the accompanying drawings, in which-- Figure l is a top view of a key-frame of my invention. Fig. 2 is a vertical cross-section on an enlarged scale, the line 0 c, Fig. 1, indicating the plane of section. Fig. 3 is a section on the line is k, Fig. 2, said figure being on a still larger scale than Fig. 2. Fig. 4is an end view of the screw which regulates the position of the key-frame.

The object of this invention is to so construct the key-frame and its connections that the touch of the keys can be regulated at will, and so, also, that any shrinkage of thekey-frame or key-bottom can be promptly and conveniently counteracted.

The invention consists, principally, in combining a separate key-frame with a supporting key-bottom and with a special screw, or rather set of screws, for drawing the key-frame into any desired position, as hereinafter described.

In the drawings, the letter A represents the key-bottom of a piano-forte, which is usually, or for the purposes of this invention may be, a solid bottom of wood.

Bis the key-frame, which is composed of the back rail, or, balance-rail, b, and front rail, (1, and of the cross-pieces e c. This key-frame B is at its back portion, by strong screws or fasteners f, secured to the back portion of the keybottom. Screws {1 may also serve to secure the key-frame, the balance-rail b, and the keybottom A together.

0 is one of the keys'of a piano, and hthepin on the balance-rail, which serves as a pivotal connection for said key. The front rail, (1, of the frame B carries the front key-pin, i, and a series of puncheons, j.

In the drawings, particularly in Fig. 2, an open space will be observed at Z between the lower face of the front portion of the key-frame B and the upper face of the key-bottom A. This open space is left there for the purpose of enabling a set of screws, D D, to regulate the elevation of the front part of the key-frame B, and thereby the height of the puncheons j si in ultaneously-th at is to say, the high er these puncheons stroke of each key 0. The screws D are placed, by preference, in the front portions of the crosspieces 6 of the key-frame, so that where the key-frame has four such cross-pieces it will havefour such screws, D. Each of these screws D has a threaded shank, m, which engages with the wood-work of the key-bottom A, as in Fig. 3. The lower end ofthe screw Dis squared, as at a, or otherwise constructed to be readily gripped by a wrench or a screwdriver. Thus the screw D is turned from below to regulate the extent to which its upper portion projects above the key-botton1 A.

Above the threaded portion at the screw D has a smooth shank, 0, which traverses the main part of thekey-frameB. A loose washer, p, rests on the threaded portion m and serves as a support for the lower side of the key-frame 1-3. A recess, q, is out into the upper face of the key-bottom A, for receiving the washer p whenever the key-frame'is drawn down as far as possible. The uppermost end of the screw D is squared, as at r, and threaded at its corners. Upon this squared portion 0 is fitted a washer, s, having a square hole, so that it cannot turn on the screw, and over this washer is placed a nut, t, which engages the threaded corners of the squared portion 1' of the screw. Inasmuch as the washer 8 cannot revolve on the screw, it is not liable to jar the nut t loose. For the reception of the washer and nut s t a recess, a, is formed in the upper face of the key-frame B.

In case the key-bottom by warping should spring the key-frame out of shape, and thereby vary the space lor the height of the puncheons j, it is only necessary to turn the screws D D and set the puncheons back to the desired height.

The player can also by the use of this in vention give to the keys of his instrument a greater or less degree of motion by adjusting the puncheons j to the desired height.

I am aware that adjustable puncheons are old; but they are impracticable, as each has to be adjusted by itself, which renders it imposare placed the shorter will he the sible to secure a uniform touoh'for a set of keys, and also that a screw has been used for adjusting the balance-rail.

I claim-- 1. In a piano, the combination of the keybottom A with the key-frame B, secured at one end to said key-bottom, and regulatingscrews D, bearing against the other end of said key-frame, all arranged for leaving a space, Z, between the front portion of the key-bottom and key-frame, as specified.

2. The combination ofthekey-bottom A, and key-frame B, carrying a series of puncheons,

j,with the regulating-screws D, bearing against the front portion of the key-frame for simultaneously adj usting said puncheons, as specified. 3. The screw D, having wrench-head n at lower part, threaded portion on, smooth portion 0, and squared and threaded upper portion, 1', in combination with the washers p s and nut t, for use on the key-bottom A and keyframe B, as herein shown and described.

PAUL GMEHLIN. Witnesses:

GUSTAV SOHNEPPE, HARRY M. TURK. 

